Arrangement for pulling a tube of heat-shrinkable plastic downwardly over a stack of goods

ABSTRACT

For enclosing a stack of goods in a sheath of a heat-shrinkable plastic material, the plastic material is supplied in the form of a flattened tube pleated along its longitudinal edges. Initially the tube is gradually opened by spreading its contacting flattened surfaces and pleated edges and then individual spaced pleated portions along each edge are gripped by pairs of conveyors for pulling each of the pleated edges in an opposite direction so that the tube is opened into a generally rectangular shape. After passing downwardly from the conveyors, the lower end of the opened tube is gripped interiorly and the gripping members are moved laterally outwardly stretching the tube to a desired extent and then the gripping members pull the tube downwardly until the stack of goods is partially enclosed and the tube is spaced outwardly from contact with the goods. As the downward movement of the tube is interrupted, a section of the tube is severed and welded closed at its upper end. The severed section is displaced laterally from engagement with the conveyors and the downward pulling action is then continued until the section of tube encloses the stack of goods.

United States Patent 1 [111 3,925,964

Birkenfeld et al. Dec. 16, 1975 ARRANGEMENT FOR PULLING A TUBE OF [57] ABSTRACT HEAT'SHRINKABLE PLASTIC For enclosing a stack of goods in a sheath of a heat- DOWNWARDLY OVER A STACK OF shrinkable plastic material, the plastic material is sup- OD plied in the form of a flattened tube pleated along its [75] Inventors: Richard Birkenfeld, Sudring; longitudinal edges. Initially the tube is gradually Friedrich wieligmann, Sennlich, opened by spreading its contacting flattened surfaces both of Germany and pleated edges and then individual spaced pleated portions along each edge are gripped by pairs of conl l Asslgneci Flrma MOlleI'S, Maschmenfabflk, veyors for pulling each of the pleated edges in an op- Bcckum, Germany posite direction so that the tube is opened into a gen- [22] FiledZ Dec. 26, 1974 erally rectangular shape. After passing downwardly from the conveyors, the lower end of the opened tube [2]] Appl' RIO-1536397 is gripped interiorly and the gripping members are moved laterally outwardly stretching the tube to a del l Foreign Application Priority Data sired extent and then the gripping members pull the May 11 1974 Germany 2422935 tube downwardly until the stack of goods is partially enclosed and the tube is spaced outwardly from [52] US. Cl 53/183; 53/384 contact with the goods. As the downward movement [51] Int. Cl. .t B65B 43/34 of the tube is interrupted, a section of the tube is sev- [58] Field of Search 53/183, 384 ered and welded closed at its upper end. The severed t l section is displaced laterally from engagement with [36] References C'ted the conveyors and the downward pulling action is then UNITED STATES PATENTS continued until the section of tube encloses the stack 3.62l,638 ll/l97l Grockc 53/183 x of goods- 3,676,98() 7/1972 Engclhardt ct al. 53/183 Primary E.\'aminerTravis S. McGehee 14 Claims 4 Drawing Figures Attorney, Agent, or Firm-Toren, McGeady and Stanger 7 I g l l l l l l l I l i 1 t I t 45] I ll l l I l i I e l l l l l l t l T1" l l l6 I: l I I l r 1 1 1 ll H l 1 l l I l I to-i 1E1 US. Patent Dec. 16,1975 Sheet2of4 3,925,964

U.S. Patent Dec. 16, 1975 Sheet3 0f4 3,925,964

FIG. 3

U.S. Patent Dec.16, 1975 Sheet4of4 3,925,964

FIG. 4

ARRANGEMENT FOR PULLING A TUBE OF HEAT-SHRINKABLE PLASTIC DOWNWARDLY OVER A STACK OF GOODS SUMMARY OF THE INVENTION The present invention is directed to an arrangement for pulling a tubular section of heat-shrinkable plastic downwardly over a stack of goods where the tubular section is taken from a supply of a flattened plastic tube with pleated longitudinally extending edges, with the flattened tube being gradually opened first by a guide member and then by oppositely directed pairs of conveyors until the desired shape is attained for passing over the stack of goods, then gripping members are inserted into the lower end of the tubular section and are displaced outwardly for holding the section in the shape required for passage over the stack of goods so that no contact between the goods and the tubular section takes place and then moving the gripping members downwardly and pulling the tubular section over the stack of goods.

There are a number of known arrangements for gripping a tube of plastic material in the range of its pleated lateral edges, spreading the edges apart and pulling the tube downwardly over a stack of goods, such as disclosed in German Pat. No. 1761895. In another known arrangement, note German Pat. No. 1940738, after the preliminary opening of the tube, each of its pleated edges are run through vertically moving wedge plates positioned above a separating and welding unit and then are moved between clamping jaws which when closed open the tube to the desired expanded shape and then pull it downwardly over the stack of goods. In this embodiment, threading the pleated edges between the clamping jaws which extend for substantially the entire height of a tube hood presents certain problems. Further, the tube has a pleated portion held between each of the clamping jaws as it is pulled over the stack of goods and, as a result, after the jaws are opened the tubular ,section is in a much more expanded state than is actually required for pulling the tube in contact-free relation over the stack of goods. Not only is there a considerable additional expenditure of the material in the tube itself, but the tube materials must be capable of shrinking within wide limits and considerable amounts of heat must be applied to achieve the shrinkage, so that the tubular section tightly encloses the stack of goods. This particular wrapping operation is disadvantageous for goods which are packed in heatsensitive materials.

Another arrangement having similar disadvantages was exhibited at lnterpack 1973 in Dusseldorf by Fernholt and Giertsen and involved the use of an accordion shaped tube delivered from a prespreading mechanism so that it is gripped in the range of its pleated edges by a double conveyor belt structure which extends first outwardly and then downwardly in such a way that the accordion tube is guided through the conveyor belts and pulled over the stack of goods. The release of the accordion tube at the end of the enclosing operation is effected by a separating movement of the inner one of the conveyor belts in each of the double conveyor belts. In addition to the use of the larger cross section of tube than is actually required for contact-free movement over the stack, the cost of the structure for releasing the pleated tube edges at the end of the enclosing operation is considerable.

In another known arrangement, note German Pat. No. 2,027,648, a tube is spread by means of suction devices and then is further expanded by rods moving into the opened tube and is pulled in the expanded state over the stack of goods. This arrangement avoids the use of an increased cross sectional size of the tube,

however, because of the rods used for expanding the tube the overall structure of the apparatus has a relatively great height and it is necessary that the stack of goods be positioned at a relatively high location on the apparatus frame, since the tube must initially be engaged by the rods above the stack, then pulled downwardly about the stack and subsequently further downward movement of the expansion rods is necessary to withdraw the rods from the tube after the tube has been positioned over the stack.

Therefore, the primary object of the present invention is to provide an arrangement for pulling a tube over a stack of goods with the tube having an optimum cross section for enclosing the goods and where the overall height of the apparatus employed is maintained at a minimum with a resultant reduction in the cost of the apparatus.

To solve the problems experienced in the past in enclosing a stack of goods with a heat shrinkable plastic, in the present arrangement a combination of features are employed including:

a. two pairs of endless revolving conveyor belts located along the opposite sides of a rectangular space and arranged to travel in opposite directions for grasping pleated portions of a partially opened pleated edged tube for continuing the opening operation;

b. gripping means arranged to be positioned below the outlet ends from the conveyor belts for holding and spreading the tube and for moving it in the downward direction; and

c. displacing members each associated with one of the pair of conveyor belts and arranged to withdraw the pleated edges from the conveyor belts after a section of the tubing has been severed and welded at its upper end at a position located above the conveyor belts.

With such an arrangement it is possible to open the flattened pleated tube without any problems and to pull it downwardly over the stack of goods with the cross section of the tube being sufficient to enclose the stack in a contact-free manner as is moved downwardly without any waste in the plastic material forming the tube and, further, the arrangement also provides a particularly simple release of the tube section after the completion of the stack enclosing operation.

It is particularly advantageous if the device for displacing the tubular section from the conveyors is a pivotally mounted lever associated with each pair of conveyors. The lever is located above and extends substantially parallel to the pair of conveyor belts with its pivoted end located adjacent the downstream end of the conveyor belts. Accordingly, when the lever is pivoted its free end moves downwardly toward the inlet end to the conveyors and commences the removal of the tubular section from between the cooperating conveyor belts. By this arrangement of the lever, it is possible to effect the withdrawal of the tubular section from between the conveyor belts so that an automatic release is effected as the belts continue to run.

The structure used for gripping the lower end of the tubular section is provided by upright posts of a relatively low height which can be displaced upwardly into the open end of the tubular section and then moved apart to stretch the section to its desired shape for passage over the stack of goods. With the upright posts gripping the lower end of the tubular section, it can be pulled downwardly over the goods and the low height of the posts affords easy insertion into and withdrawal from the lower end of the tubular section and assures a considerable reduction in the overall height of the apparatus used for enclosing the stack of goods.

Preferably, the upright posts are formed by short rod members with a rounded-off head which extends laterally outwardly from the rod. This construction of the posts assures that the lower end of the tubular section is firmly held as it is pulled downwardly over the stack and assures ease in withdrawing the upright post after the completion of the downward movement of the tubular section.

The pairs of conveyor belts which grip the pleated portions of the tube and pull them apart are pivotally mounted at their inner or adjacent ends so that the outer ends can be pivotally displaced for adaptation to different stack sizes. Preferably, the pair of or double conveyor belts are arranged for pivotal movement about the inner reversing wheel axle of the lower one of the conveyor belts. With this arrangement there is no displacement of the point at which the tube is introduced into the inlet ends of the pair of conveyors.

Moreover, it is also possible to supportthe pairs of conveyor belts spaced from one another in the lateral direction so that they can be moved inwardly or outwardly in that lateral direction for adapting to different stack sizes. In other words, the conveyor belts are arranged so that they can define a variable rectangularly shaped space in accordance with the different stack sizes to be enclosed by the heat-shrinkable plastic tube.

Similarly, the upright posts which are positionable within the lower end of the tube after it leaves the conveyors, can be adjusted for adaptation to various stack sizes.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a side view of an apparatus embodying the present invention and positioned to commence the downward movement of an opened flattened tube over a stack of goods;

FIG. 2 is a side view similar to FIG. 1 but with the open tube moved downwardly partially enclosing the stack of goods;

FIG. 3 is a view similar to FIGS. 1 and 2 but with the tube pulled downwardly for completely enclosing the stack of goods and with a next section of the tube in position for enclosing another stack of goods; and

FIG. 4 is a top view of a portion of the apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION In the drawing an upright frame 1 is shown spanning the track 2 on which is supported a stack of goods 3. As illustrated in FIG. 4, the frame 1 has a rectangularly shaped transverse c'ross section and it extends laterally outwardly from and upwardly above the track 2 so that the upper surface of the stack of goods 3 is located below the upper end of the frame.

Mounted on one side of the frame 1 is a roll 4 on which a flattened tube 5 of heat-shrinkable plastic material is wound with both of the longitudinally extending sides or edges of the tube provided with a plurality of pleats. Initially, the flattened tube 5 is drawn upwardly from the roll 4 over guide rollers 6 and driving rollers 7 from which it is fed downwardly toward a guide element 8. The guide element 8 has an inverted V-shaped and is mounted for movement in the vertical direction from the position shown in FIG. 1 to the position shown in FIG. 2, the purpose of the two different positions will be explained later. Spaced laterally outwardly from the guide element 8 in the position shown in FIG. 1 and below the guide element 8 in the position shown in FIG. 2 are a cutting unit 9 and a welding unit 10. As can be seen in FIG. 2, the cutting unit 9 and the welding unit 10 can be operated when the guide element 8 is moved into its upper position.

Immediately below the guide element 8 on each side of the frame, note FIG. 4, are two pairs of conveyor belts 11 having their inlet ends arranged to receive the tube from the guide element. Each pair of conveyors extends outwardly at a slight downward slope. Each pair of conveyor belts consists of an upper belt and a lower belt with the reversing axle of the lower conveyor belt at the inlet end of the pair of conveyor belts being pivotally mounted so that the downwardly sloping orientation of the belts can be varied, note the arrows in FIGS. l-3, for changing the distance measured in the horizontal direction between the inlet and outlet ends of the pair of conveyor belts. As can be noted in FIG. 4, the two pairs of conveyor belts on the opposite sides of the frame define two sides of a rectangular space the dimensions of which can be varied by pivoting the outlet ends of each pair of conveyor belts and also by varying the horizontal distance between the double pairs of conveyor belts on the opposite sides of the frame 1.

Each pair of conveyor belts 11 has an associated pivotally mounted lever 12 which extends in substantially parallel relation with its associated conveyor belts. The lever 12 is pivotally mounted on the fixed point 13 by means of a pivoting mechanism 14. As illustrated in FIG. 4, each lever 12 is spaced slightly inwardly of the pair of conveyor belts with which it is associated and is positioned above the upper one of the conveyor belts.

Mounted approximately in each of the four corners of the frame 1 are endless revolving chains 15 which extend for about the full height of the frame, that is, for the full height of its upright members. A carriage 16 is mounted on each of the chains 15 and extends inwardly toward the outlet end of the pairs of conveyor belts. At the inner end of each carriage 16, a short rod or upright post 17 extends upwardly from the carriage and terminates in a rounded-off enlarged head 18, that is, the surfaces of the rounded head project outwardly from the surfaces of the upright post 17. Each of the upright posts is adjustable both in its longitudinal direction and in a direction transverse to the longitudinal direction for adaptation to the different dimensions above the stacks of goods 3 to be wrapped or enclosed by the heat-shrinkable plastic material.

Method of Operation of the Apparatus When the operation of the apparatus is commenced, the flattened tube 5 is threaded over the guide rollers 6, between the driving rollers 7 and then downwardly over the V-shaped guide elements, in the position shown in FIG. 1, so that the opening of the flattened tube has commenced. As the opposite edges of the tube pass downwardly into the inlet ends of the two pairs of conveyor belts 11, a longitudinally extending pleated section of the tube is gripped between the upper and lower conveyor belts on each side of the guide element and the spreading or opening of the tube is continued. As viewed in FIGS. 1*3, the flattened surfaces of the tube extend perpendicularly to the plane of the figures while the pleated sides .of the tubes are arranged in the plane of the figures. As a result, the pleated sides are gradually open and the flattened surfaces are pulled apart as the tube moves downwardly between the cooperating conveyor belts 11.

After the lower end of the tube has moved outwardly and downwardly a certain distance below the outlet ends of the pairs of conveyor belts 11, for example, about 30 cm, the drive of the driving rollers 7 is cut off and the carriages 16 are moved upwardly for introducing the upright posts 17 within the open end of the tube. With the upright posts 17 inserted into the tube the carriages 16 are stopped and the posts are moved transversely of the height dimension of the frame 1 toward the periphery of the frame, that is, in the outward direction, so that the lower end of the tube is tightly held by the posts 17 in a rectangular form sufficient to pass downwardly over and outwardly from the four comers of the stack, note FIG. 1. As can be noted in FIGS. 1-3, the upright posts 17 pass downwardly laterally outwardly from the sides of the stack 3 so that the tube passes in contact-free relation with the stack.

Next the driving rollers 7, the pairs of conveyor belts 11, and the chains are actuated simultaneously and the tube is pulled downwardly about the upper portion of the stack 3 into the position shown in FIG. 2. When this position has been reached, the guide element 8 is displaced upwardly to the position in FIG. 2 and the cutting unit 9 and the welding unit 10 are actuated for cutting off a section of the tube and welding it closed so that it can form a cover over the top of the stack of material.

The various driving means used for conveying the tube downwardly, which are cut off during the cutting and welding operation, are restarted so that the section of tubing as shown in FIG. 2 again starts to move downwardly. However, at this point the mechanism 14 is actuated and pivots each of the levers 12 about the fixedaxis 13 so that the lever is swung downwardly, note the arrow in FIG. 2, from the position shown in full lines to that shown in chain lines. Because of the position of the lever spaced inwardly of the conveyors it pulls or displaces the pleated sections of the tube held between each pair of conveyors. At the same time that the lever 12 is removing the pleated sections of the tube from between the conveyors, the carriages 16 are moving downwardly bringing the rods along with them and drawing the tubular section over the stack of goods until it is completely covered by the tube section which is closed at its upper end forming a hood or cover over the'stack, note FIG. 3. With the tube section displaced from between the conveyors and the lever 12 returned to its normal position above the conveyors, the guide element 8 is again lowered and the driving rollers actuated so that the lower end of the flattened tube is ready to commence a new cycle downwardly between the conveyor belts 11. Note FIG. 3 where the stack of goods 3 is enclosed by the section of tube and the following open end of the tube has passed downwardly between the conveyors and is ready to commence another stack enclosing cycle. With the tube section covering the stack of goods, as shown in FIG. 3, the downward movement of the carriages 16 withdraws the posts 17 from the tube section and downward movement of the chains 15 is terminated. The covered stack of goods 3 enclosed by the tube section of heat-shrinkable plastic material can be moved along the track 2 out of the frame for any finishing operations required and a new stack of goods can be placed within the frame, after which another cycle of operation is commenced.

It can be appreciated that the embodiment of the invention described above can be modified in many respects without departing from the spirit of the invention. For instance, gripping tongs could be used in place of the upright posts 17 and the preliminary spreading or opening action of the flattened tube could be formed by suction devices or other opening elements.

We claim:

1. Apparatus for placing a tube of heat-shrinkable plastic over a stack of goods by moving the tube over the goods, the tube is originally supplied flattened in a roll with longitudinally extending pleating sides extending along the flattened side of the tube, the apparatus including first means for removing the flattened tube from the roll and partially opening the tube, second means for receiving the partially opened tube from said first means and for opening and spreading the tube, third means for severing a section of the tube and closing the severed end after a partial movement of the tube by said second means, and said second means arranged to move the severed section of the tube over the goods, wherein the improvement comprises that said second means includes conveyor means arranged to receive the partially opened tube at each of its opposite pleated sides from said first means for moving the tube from said first means and for continuing to spread the pleated sides while holding at least a portion of the pleated sides, said conveyor means having an inlet end arranged to receive the partially opened tube from said first means and an outlet end, gripping means located adjacent the outlet end of said conveyor means for engaging the opened end of the tube moving from the outlet end and for spreading the tube to a size sufficient for movement over the goods in contact-free relation therewith, and displacing means associated with said conveyor means and being movablfdisplac'eable for withdrawing the pleated portions of the tube from engagement with said conveyor means so that the downward movement of the severed tubular tube section can be completed for movement over the stack of goods.

2. Apparatus, as set forth in claim 1, wherein said conveyor means comprises four pairs of conveyors with each pair comprising a first conveyor belt and an oppositely disposed second conveyor belt arranged so that a pleated portion of the tube can be held and moved between them, each of two of the four said pairs of conveyors defining one side of a generally rectangular space, said two pairs of conveyors defining one side being in end-to-end alignment at the inlet end of said conveyor means with the adjacent ends each arranged 7 to receive a spaced pleated portion of the partially opened tube passing from said first means, and each pair of conveyors in the two pair of said conveyors along one side of the rectangular space arranged to move the pleated portion of the tube held between them in opposite directions.

3. Apparatus, as set forth in claim 2, wherein each said pair of conveyors is pivotally mounted at its inlet end so that the outlet end of each said pair of conveyors can be displaced relative to the inlet end for accommodating the opening of the tube to the cross-sectional size of the goods to be covered.

4. Apparatus, as set forth in claim 2, wherein said displacing means comprises a pivotally displaceable lever associated with each said pair of conveyors and arranged to be pivoted in a path intercepting the path of movement of the tube between the inlet and outlet ends of said pair of conveyors with which it is associated for displacing the pleated portion of the tube from gripped engagement between said pair of conveyors.

5. Apparatus, as set forth in claim 4, wherein each said first conveyor is positioned above said second conveyor with which it forms a pair, each said pivotally displaceable lever is positioned upwardly from the upper one of the pair of said conveyors with which it is associated and is arranged to extend in generally parallel relation with said pair of conveyors and also to extend for approximately the length of said conveyors, each said lever being pivoted at the end adjacent the outlet end of said conveyors with which it is associated, each said lever spaced inwardly from said pair of conveyors with which it is associated toward said pair of conveyors on the opposite sides of the rectangular space defined by the conveyors, and means for pivoting each said conveyor so that it moves downwardly from its position in parallel relation with said pair of conveyors into contact with the tube held by each said pair of conveyors for displacingthe tube from engagement between each said pair of conveyors.

6. Apparatus, as set forth in claim 2, wherein each said pair of conveyors is arranged to incline outwardly and downwardly from its inlet end relative to the other said pair with which it defines one side of a generally rectangular shape, said gripping means comprises a plurality of upright posts with each said upright post arranged to be aligned below one comer of the rectangular space defined by the outlet ends of said conveyors, and means associated with said upright posts so that they can be moved in the upward-downward direction and transversely thereto in the inward-outward direction for effecting insertion into the lower end of the tube as it passes downwardly from the conveyors for further spreading the lower end of the tube out- 8 wardly and for moving the tube downwardly over the stack of goods.

7. Apparatus, as set forth in claim 6, wherein said upright posts are of a relatively short height so that they can be inserted into the open lower end of the tube for holding and opening the lower end of the tube leaving the remainder of the upwardly extending corners of the tube free between said upright posts and the outlet ends of said conveyors.

8. Apparatus, as set forth in claim 7, wherein the upper end of each said upright post has a thickened head portion extending laterally outwardly from the lateral surface of said post.

9. Apparatus, as set forth in claim 7, wherein said gripping means includes a carriage for each said upright post, an upright support member, said carriage mounted on said upright support member for movement in the upward-downward direction, and said upright post secured to said carriage and movable therewith in the upward-downward direction.

10. Apparatus, as set forth in claim 9, wherein said carriage is arranged to move transversely of the upward-downward direction for moving said post attached thereto for spreading the open end of the and for adjusting the position of said post to accommodate various transverse cross-sectional sizes of the stack of goods.

11. Apparatus, as set forth in claim 3, wherein each said first conveyor is positioned above said second conveyor with which it forms a pair, each said pair of conveyors is arranged to incline outwardly and downwardly from its inlet end relative to the other said pair with which it defines one side of a generally rectangular space, each said pair of conveyors is pivotally mounted about the axis at the inlet end of the lower one of said conveyors of each said pair.

12. Apparatus, as set forth in claim 3, wherein each said pair of conveyors is mounted for movement toward and away from the pair of said conveyors on the opposite side of the rectangular space defined by said four pairs of conveyors for adjusting the position of said conveyors to the cross-sectional sides of the stack of goods to be enclosed.

13. Apparatus, as set forth in claim 9, including an upright frame, said upright support members for said carriages forming the corner members of said frame, said frame also forming a support for said first means, said third means and said displacing means.

14. Apparatus, as set forth in claim 10, including a vertically endless chain mounted on each said upright support member and arranged to be driven in the upwardand downward direction, and each said carriage attached to one of said endless chains for movement in the upward-downward direction. 

1. Apparatus for placing a tube of heat-shrinkable plastic over a stack of goods by moving the tube over the goods, the tube is originally supplied flattened in a roll with longitudinally extending pleating sides extending along the flattened side of the tube, the apparatus including first means for removing the flattened tube from the roll and partially opening the tube, second means for receiving the partially opened tube from said first means and for opening and spreading the tube, third means for severing a section of the tube and closing the severed end after a partial movement of the tube by said second means, and said second means arranged to move the severed section of the tube over the goods, wherein the improvement comprises that said second means includes conveyor means arranged to receive the partially opened tube at each of its opposite pleated sides from said first means for moving the tube from said first means and for continuing to spread the pleated sides while holding at least a portion of the pleated sides, said conveyor means having an inlet end arranged to receive the partially opened tube from said first means and an outlet end, gripping means located adjacent the outlet end of said conveyor means for engaging the opened end of the tube moving from the outlet end and for spreading the tube to a size sufficient for movement over the goods in contact-free relation therewith, and displacing means associated with said conveyor means and being movably displaceable for withdrawing the pleated portions of the tube from engagement with said conveyor means so that the downward movement of the severed tubular tube section can be completed for movement over the stack of goods.
 2. Apparatus, as set forth in claim 1, wherein said conveyor means comprises four pairs of conveyors with each pair comprising a first conveyor belt and an oppositely disposed second conveyor belt arranged so that a pleated portion of the tube can be held and moved between them, each of two of the four said pairs of conveyors defining one side of a generally rectangular space, said two pairs of conveyors defining one side being in end-to-end alignment at the inlet end of said conveyor means with the adjacent ends each arranged to receive a spaced pleated portion of the partially opened tube passing from said first means, and each pair of conveyors in the two pair of said conveyors along one side of the rectangular space arranged to move the pleated portion of the tube held between them in opposite directions.
 3. Apparatus, as set forth in claim 2, wherein each said pair of conveyors is pivotally mounted at its inlet end so that the outlet end of each said pair of conveyors can be displaced relative to the inlet end for accommodating the opening of the tube to the cross-sectional size of the goods to be covered.
 4. Apparatus, as set forth in claim 2, wherein said displacing means comprises a pivotally displaceable lever associated with each said pair of conveyors and arranged to be pivoted in a path intercepting the path of movement of the tube between the inlet and outlet ends of said pair of conveyors with which it is associated for displacing the pleated portion of the tube from gripped engagement between said pair of conveyors.
 5. Apparatus, as set forth in claim 4, wherein each said first conveyor is positioned above said second conveyor with which it forms a pair, each said pivotally displaceable lever is positioned upwardly from the upper one of the pair of said conveyors with which it is associated and is arranged to extend in generally parallel relation with said pair of conveyors and also to extend for approximately the length of said conveyors, each said lever being pivoted at the end adjacent the outlet end of said conveyors with which it is associateD, each said lever spaced inwardly from said pair of conveyors with which it is associated toward said pair of conveyors on the opposite sides of the rectangular space defined by the conveyors, and means for pivoting each said conveyor so that it moves downwardly from its position in parallel relation with said pair of conveyors into contact with the tube held by each said pair of conveyors for displacing the tube from engagement between each said pair of conveyors.
 6. Apparatus, as set forth in claim 2, wherein each said pair of conveyors is arranged to incline outwardly and downwardly from its inlet end relative to the other said pair with which it defines one side of a generally rectangular shape, said gripping means comprises a plurality of upright posts with each said upright post arranged to be aligned below one corner of the rectangular space defined by the outlet ends of said conveyors, and means associated with said upright posts so that they can be moved in the upward-downward direction and transversely thereto in the inward-outward direction for effecting insertion into the lower end of the tube as it passes downwardly from the conveyors for further spreading the lower end of the tube outwardly and for moving the tube downwardly over the stack of goods.
 7. Apparatus, as set forth in claim 6, wherein said upright posts are of a relatively short height so that they can be inserted into the open lower end of the tube for holding and opening the lower end of the tube leaving the remainder of the upwardly extending corners of the tube free between said upright posts and the outlet ends of said conveyors.
 8. Apparatus, as set forth in claim 7, wherein the upper end of each said upright post has a thickened head portion extending laterally outwardly from the lateral surface of said post.
 9. Apparatus, as set forth in claim 7, wherein said gripping means includes a carriage for each said upright post, an upright support member, said carriage mounted on said upright support member for movement in the upward-downward direction, and said upright post secured to said carriage and movable therewith in the upward-downward direction.
 10. Apparatus, as set forth in claim 9, wherein said carriage is arranged to move transversely of the upward-downward direction for moving said post attached thereto for spreading the open end of the and for adjusting the position of said post to accommodate various transverse cross-sectional sizes of the stack of goods.
 11. Apparatus, as set forth in claim 3, wherein each said first conveyor is positioned above said second conveyor with which it forms a pair, each said pair of conveyors is arranged to incline outwardly and downwardly from its inlet end relative to the other said pair with which it defines one side of a generally rectangular space, each said pair of conveyors is pivotally mounted about the axis at the inlet end of the lower one of said conveyors of each said pair.
 12. Apparatus, as set forth in claim 3, wherein each said pair of conveyors is mounted for movement toward and away from the pair of said conveyors on the opposite side of the rectangular space defined by said four pairs of conveyors for adjusting the position of said conveyors to the cross-sectional sides of the stack of goods to be enclosed.
 13. Apparatus, as set forth in claim 9, including an upright frame, said upright support members for said carriages forming the corner members of said frame, said frame also forming a support for said first means, said third means and said displacing means.
 14. Apparatus, as set forth in claim 10, including a vertically endless chain mounted on each said upright support member and arranged to be driven in the upward and downward direction, and each said carriage attached to one of said endless chains for movement in the upward-downward direction. 